Question

find the length of the bridge. of a train 130 metres long and travelling at 45 km/ hr can cross in 30 seconds?

Answer 1

Let the length of the bridge be x meter ; then
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Speed = 45 km/hr
= 45 × 1000/3600 m/sec
= 450/36
= 12.5 m/s
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Time = 30 sec
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Distance = length of bridge+ length of train
= x+130
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Speed = Distance/Time
12.5 = (x+130)/30
x+130 = 375
x = 375-130
x = 245
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Hence the length of the bridge is 245 m

Answer 2

Answer:

245

Step-by-step explanation:

x = Length of the Bridge.

Total Distance = ( x + 130) m

Speed = 45 * (5/18) m/s

           = 25/2 m/s

So,

Speed = Distance/Time = (x+130)/30 = 25/2

                                       or, x + 130 = 375

                                       or, x = 245

Length of the Bridge = 245 m